The present invention generally relates to orthodontic appliances, and more particularly to a buccal end tube device for selectively orienting an orthodontic arch wire relative to a tooth.
Various buccal tubes or end tubes are already known which are positioned on a tooth to receive the end of an arch wire of an orthodontic arch. The buccal tubes are usually placed on one of the molar teeth. As is well known in the art, the section of the arch which extends between the cuspids to the first molars is generally straight. However, depending on the precise position in which the buccal tube is mounted on the buccal surface of the molar, the axis of the aperture through the buccal tube will vary relative to the straight line arch wire section which extends distally towards the molars. Normally, the buccal tube is so mounted on a normally positioned molar so that it has a distinguished inclination relative to the undeflected arch wire extension. Forcing the arch wire extension through the buccal tube, in such a case, causes the molar on which the buccal tube is mounted to rotate mesiolingually or distobuccally. When the molar is oriented in a desired position, however, such rotation is undesirable and, ideally, the arch wire extension only passes through the buccal tube in a passive state without generating forces on the tube. Such passive relationship between the arch wire extension and the buccal tube can sometimes be achieved by precise positioning of the buccal tube so that its axis is substantially aligned with the axis of the undeflected arch wire extension. There have been numerous problems in the mounting of buccal tubes. Firstly, it is not always possible or practical to precisely mount the buccal tubes in such a manner that their axis will align with the axis of the undeflected arch wire extension. Frequently, a technician welds the tube inadvertently on a slightly offset buccal surface from that surface which would provide such coaxial alignment. Depending where the buccal tube is welded on a tooth band, if any misalignment results, the molar tooth on which the tube is mounted will either be forced to rotate distobuccally or distolingually, mesiolingually, or mesiobuccally.
One approach which has been taken to achieve alignment in some cases has been the bending of the arch wire lingually so as to change the orientation of the axis of the arch wire extension to coincide with the previously welded or positioned end tube or buccal tube. Very careful attention must be given to the manner in which molar bends are formed, because the previously mentioned straight line from cuspid to molar ends at the molar. If the buccal surface of the molar follows the same straight line, the tooth would be rotated distobuccally. For example, a simple bend may be proper over the mesiobuccal molar cusp, but a double bend or bayonet bend is required if the bend is positioned more mesially. The utilization of the bends in the arch wire extensions to provide alignment presents a second problem known in the prior art which arises when the arch wires move with the movement of teeth during corrective action. Thus, while a bent arch wire extension may initially provide passive engagement with an end tube, movement of the arch wire relative to the end tube may generate the very rotating forces which intended to be avoided by the application of the bends. Furthermore, excessive movement of either the arch wire or of the tooth on which end tube is mounted may result in undesired engagement between the end tube and the bend whereby further movement of one is prevented by the other of the engaging elements.
Although passive engagement is frequently desired at the end tubes, it is sometimes desired to rotate the molar either distobuccally or distolingually when a molar is not in its desired position. In such cases, the axis of an arch wire extension must be engaged with a properly mounted end tube whose aperture axis forms a predetermined or desired angle relative to the axis of the arch wire extension. Most buccal tubes known in the art provide apertures parallel with the welding flange, thereby forming no angle therewith. Some buccal tubes are provided with a 5.degree. angle relative to the welding flange. Such angled tubes are utilized for distolingual rotation to essentially counteract the distobuccal or mesiolingual rotation associated with normally positioned molars and straight wire extensions described above.
The buccal tubes, either with 0.degree. or 5.degree. offsets, have not, however, offered the flexibility required in the utilization of buccal tubes. If another inclination or offset is desired, this is not possible except by removing the end tube from the band and reconnecting it on another buccal surface thereof. The latter approach is very time consuming and cumbersome both to the technician as well as to a patient. It also frequently happens that the desired orientation of the end tube aperture changes as the teeth move in response to the forces generated by the arch. Clearly, the prior art end tubes do not permit changes in the angular orientation of the end tubes without removing the latter and repositioning it.
Another feature of the known end tubes has been that they have normally been used merely for the purpose of preventing rotation of a molar tooth in one direction or another. The known types of end tubes do not permit convenient orientation of the arch wire therethrough which would result or cause the molar to selectively tip or rotate in one direction or another. To achive such corrective action, the end tube must be previously welded to a band in the precisely desired fashion. As in the case of rotation, the number of inclinations available for inserting an arch wire extension for tipping purposes is severely limited.